This article looks at the treatment of languages in the communities in Spanish territory, which apart from Spanish have another language. At the beginning we discuss some questions which are relative to social cohesion in those territories where more than one language is spoken and we defend bilingual education as a good instrument in favour of it. At the same time we look at the concept of bilingual education and the assumptions that it bears in respect of the learning of languages. In this sense we discuss the conditions of acquisition of language and its appearance in the area of bilingual education